This invention relates generally to electronically commutated motors, and more particularly, to an input/output circuit for an electronically commutated motor which facilitates speed selection.
Electronically commutated motors (ECMs) are used in a wide variety of applications. In many applications, either discrete speed options or infinitely variable speed operation is desired. Known ECMs which permit the operating speed to be varied include resistor divided networks and a plurality of taps. The resistor divided networks operate in conjunction with the plurality of taps to enable a different operating speed to be selected for the ECM. Different hardware models, or different software limits, are required for each application. As a result, many different motor models typically must be maintained in inventory for multiple applications.
In an exemplary embodiment, an electronically commutated motor includes an input/output (I/O) unit which permits a user to select discrete operating speed options. The I/O unit is electrically connected to a connector terminal board and a microprocessor. The connector terminal board includes an electrically erasable programmable read-only memory (EEPROM), non-isolated low voltage signal connections for programming the EEPROM and speed signal connections for enabling selection of an operating speed for an electronically commutated motor.
In one specific embodiment, preprogrammed speed tables stored within the EEPROM include five different operating speeds and a low voltage variable speed. To select a speed, a voltage is applied to a combination of the speed signal connections. As a result, a cost-effective and reliable electronically commutated motor assembly is provided which increases the flexibility to the user.